Select Aquatics / Greg Sage
Originally published in “Livebearers”, Journal of the American
Livebearers Association . First published in 2003,
it was revised in 2011, where it appeared in various publications, and
was updated in September 2023 for
use by The Darter / Missouri Aquarium Society
I had kept community tanks for over 40 years, and decided around 1995 to
devote a few tanks to working with just
one line of livebearers, hoping to develop something I thought looked
good, representing better quality, consistent
color, size and finnage than what I had. I knew I didn’t have the
knowledge of genetics I thought I’d need to
introduce specific physical characteristics, but with all I had read
about careful record keeping and observing fish
closely, I thought I’d be able to “stabilize” a line toward its best
looking individuals. I believed that it shouldn’t be
too difficult to get a line to look fairly consistent, close to how I
thought it should look, producing desired,
attractive and healthy fish.
Select Aquatics has always focused on rare livebearers that were both
disappearing from the wild and from the hobby,
There are selectively bred morphs of the Characodon lateralis, audax and
other species that are not common
in the hobby coming out of Europe, but I did not want to genetically
fuss with any of those species, where the selectively
bred versions could come to represent that species in the hobby.
Also, guppy breeders established long ago that new traits do not become
established for at least 11 generations. So, as
has been documented with domestic lines of pet store platys released to
bodies of water in Florida, genetically manipulated
fish will return to their wild coloration within 3-4 generations. Also,
the effects of domestic breeding manipulation will diffuse
quickly when breeding with wild, normally colored fish.
The journey to selectively breed my own lines of fish proved to be
exciting and humbling. I found that I knew less than I
thought, but could accomplish what I wanted to accomplish by keeping at
it, and using common sense to keep track of my best
breeding individuals, maintaning the line at its best health, and
carefully raising up every fry.
In the mid- 1990s I started this process with a well planted 100 gallon
show tank filtered with a well aged wet/dry trickle
filter, a mature fluidized bed filter on the back and over 30 years
experience at keeping fish. In this large tank
I kept trays of peat beneath a ½” layer of natural pea gravel that
supported large trunks of carefully trimmed
Watersprite (Ceratopteris- they looked liked a maintained Bonsai forest)
and Vallisneria, and I had moved out all of
the fish. My goal was to have these beautiful surroundings with the big IFGA (International Fancy Guppy association)
delta tailed guppies swimming between the plants. I was willing to set
up a couple 20 gallon tanks for babies and for
quarantine. So those guppies were my first choice, yet I knew nothing
about these fish, other than that they were
In fewer words, I had absolutely no idea what I was doing.
How hard can guppies be to keep? I hadn’t talked to anyone, or read a
thing about them, thinking I knew guppies.
For the majority of my time keeping tanks I’ve always had a line or two,
and I’d kept guppies pretty heavily when I
was in high school. I came to find out that everything I needed to know
about keeping and breeding any other fish in the
hobby would be learned by keeping these high quality guppies, and the
issues I encountered.
I set out to buy the best IFGA Guppy stock I could find. Through the
classified ads in the back of fish
magazines, I contacted a couple breeders and even set up appointments to
tour their fishrooms. One room
involved a 7 hour drive to L.A. from where I was living, but it was
entirely worth the effort. I explained what I
wanted to do, and that I was willing to spend a little money to start
with a few quality fish.
The fishroom in L.A. was mindblowing. This guy had close to 200 tanks,
and most of them were 30, 50 and 90 gallon
tanks. All stocked heavily with thousands of guppies. Entire rows with
tanks on both sides, all filled with bright
delta tails- dozens of tanks that in many cases were full of the same
line of identical fish! With a great eye and
years of experience he scanned the fish as they matured, looking for
tiny advantages or flaws in any particular fish,
carefully picking his next line of breeders.
I did my best to pick every corner of his brain I could get into. “How
extensive is your record keeping?”
I asked. “ He responded "I don’t keep records. In fact I really don’t
write anything down.” He had dozens of lines.
Thousands of fish. 200 aquariums, and he doesn’t keep any records. I was
then warned that my planted 100 gallon tank
idea was not a good one, but I didn’t understand why. Today I realize
that those breeders probably figured
there wasn’t enough time in the day to explain what I needed to know.
Starting off learning to selectively breed and develop a line of fish
with fragile, high end guppies was the best thing
I could have done. Every issue I could have had with a selective
breeding program, and maintaining overly sensitive
fish was waiting for me. The lessons were priceless. You quickly learn
to establish control over each variable in your
fishkeeping and selective breeding process, and to carefully watch your
fish to better understand their care, and what
is best for them (and not just you), and how they are responding to the
developments you are introducing them to.
I bought 3 trios and ran into problems before the fish had even arrived.
To prepare for their arrival, I was told to totally
clean everything with bleach. Tanks, filters, nets, siphon hoses,
tubing, everything. All of the established biofiltration had to
be started from scratch, and for evermore any fish from outside of my fishroom had to stay outside of my fishroom. No more live
plants or gravel. These top quality fish, at close to $100 a trio back
in 1995, were coming from what I was assured were
totally disease free environments, and must be introduced to a similar
setup. The breeders I visited even kept these cute
little dipping buckets filled with a weak chlorine bath for dipping
their nets, to prevent any spread of bacteria between tanks.
Salt was maintained in the water at 1 tblsp. per five gallons of water.
Everything had to be kept clean, clean, clean.
With the salt in the water and careful, nearly obsessive observation of
the fish, I began to understand why I didn’t see plants
or gravel in any of the tanks of the champion breeders I visited. I
maintained those guppies for 5 years.
I don't do most of that today. However, my basic set up in all of the
tanks here in 2023 are influenced from those early practices,
and what I learned about the dangers of allowing mulm and debris to
build up, and where bacteria could fester in a way that could
bring down your water quality, causing disease, lack of breeding and
problems with your fish.
Gravel harbors organic waste that can contribute to fungal and bacterial
infections, and limits your control over the
cleanliness of the overall tank environment. For consistent health of
your fish, it is best to assume that mulm and debris are
never inert, and must always be kept to a minimum.
With hardier species, such as those in the commercial pet trade, all of
these precautions may not be required to keep them alive.
But to raise your fish to their best size, color, and to be as disease
resistant as possible, I needed to maintain those practices. A
large part of selective breeding is raising every fry, as mutations are
not uncommon, and losing individuals due to poor water
quality can limit your selective breeding program.
Multiple bare-bottomed single species tanks would be easier to maintain,
though they might not be much to look at, and
how the tanks look was certainly important to me. The tanks were now
bare, clean and functional, with a visual focus on the fish.
So I eventually introduced plants to provide hiding places for fry, and
to address the need for security in some fish.
A more natural environment encourages breeding and healthy spawns. Today
I maintain heavily planted
tanks for display and grow out, but with selectively bred individuals
where losing any is not an option, the tanks are simply
a single pebble layer of gravel over 1/3 to 1/2 of the tank bottom,
providing essential nitrifying bacteria area, some floating plants,
filtration, low light and heat (when necessary), and the fish.
The mechanical and biological filters are no longer the primary means of
filtration. The filters maintain the
biological health of the water, and with the in-tank livebearer-style
box filters, excess mulm and debris can pretty much be kept
in check. The main source of filtration would be water changes, and
keeping an appropriate number of fish fed so that
decaying food does not affect water quality. Today, all of my young grow
out tanks receive 10% - 15% daily water changes,
and the majority of the rest of the room receives 2 - 3 water changes
per week amounting to roughly 60%.
An ultraviolet sterilizer is not a bad idea, but does begin to get in
the way of keeping things simple and inexpensive. If you are
selective breeding to eventually build out fish for sale, keep in mind
that too much extra care could produce fish that when tossed
into a standard, minimally maintained community tank, they may not
adapt. It is not always enough to provide fish that are healthy when
they leave your facility- it is your responsibility that they are hardy
enough to withstand broad changes in water conditions and
husbandry when introduced to their new environment.
No fish can handle abuse for very long, and you want to be sure that you
do not provide extra care that the customer will not.
Fish raised with a UV sterilizer, 10% daily water changes, prophylactic
doses of salt with water changes, and possibly regular
dosing of a disease preventative are done routinely by some aquarists.
However, someone taking a fish from that level of care
and putting them into an established tank with other species, without
the sterilizer, salt, preventative medications, at slightly
different temps, diet and feeding, the new fish may not do well.
It should be assumed that all customers purchasing your fish will put
them into a quarantine tank by themselves at first.
A quarantine tank is often more about introducing the arrival to new
water qualities, husbandry and foods, and achieving best health
for them, before meeting new tank mates and adjusting to their their
So in that first Guppy breeding program I have a couple of bare bottomed
tanks, with the outside of the bottom glass plate
painted black to bring out the colors of the fish, no plants, a 100
gallon tank empty except for the clear water cycling through
brand-new filters, and a couple trios of very young, tiny, and what for
me were incredibly expensive fish.
The books I read said livebearers would require 4 tanks per strain; a
male grow-out tank, a female grow-out tank, a baby raising
tank and a mating/breeding tank. That's great until you have more than
one gravid female at a time. If you breed your line
in trios, as you should, tank space issues will present themselves
With barbs, danios, and similar egg scatterers you also need a minimum
of 4 tanks- a male adults
tank, a female adults tank (where the females can also be conditioned
separately for spawning), a breeding/ new fry tank
and a fry grow out tank. Most cichlids will require more tanks, because
they are generally larger, can be territorial,
and don’t breed in groups. Cichlids (where spawns can be 200+ fry)
require a fry grow-out tank, grow-out tanks for
young from about a month old until they pair off, and a separate tank
for each mated pair to spawn in. This
means that all tanks will be species-only tanks.
do maintain a “cull tank” that looks great with fish that show off a
little of what I am doing in the room, but they are primarily
tanks set up so that I have backup fish to use as breeders if needed.
recommend keeping a collection of portable, lightweight containers on
hand to serve as temporary “housing” as fish
are born and numbers take off. I use the 10 or 12 gallon sized, white
plastic kitchen-type trash containers, and only
use those made by Sterilite, with a few plants and a box filter. This
isn’t a plug for Sterilite- some companies use softeners
in their plastic that can be toxic to fish. I have found this to be the
case in the past with Rubbermaid products, and lost many
fish until I discovered what the problem was.
The biggest drawback to using those white trash cans in a breeding
program is that the bright white sides wash out
the color in the fish when reasonably well lit- and the color quickly
returns when put back into a normal environment.
The biggest drawback is that you are not able to observe them, which
keeps their use to a temporary basis. For the extra
female about to pop, they are perfect with a little Java moss to protect
Raising up the sexes up separately is essential with many species. With
guppies, males develop a gonopodium by their first
month. From then on their energy and time is spent chasing and courting
females or competing with one another, when you
want them eating and building finnage. Separating them puts their energy
into growth, and the differences in size when the
sexes have been grown out separately is substantial. The trick then
becomes at what point are as good as they were going
to get, but not too old to breed? That is something I’ve simply I had to
learn as I’ve been doing this. When raised separately,
they get much larger, and when choosing breeders you can then see each
fish at closest to its potential.
There is a basic rule when breeding and selling fish that was told to me
many years ago. It is a tough rule to stick to,
but is essential to any serious breeding program. And that is that if
you can't breed it, and you can't sell it, you have to get it
out of your fish room.
Successful selective breeding means culling, which I do understand the
need for. But intentionally killing fish wasn’t
something I wanted to do. Previously, when fish die it had always been a
bad thing. I once heard a comic say that he liked to
watch things die… so he bought a fish tank. I was pleased to see,
however, that even some of the most macho breeders that
shrug over killing hundreds of fish often have a pond in their back yard
full of their culls, local petshops full of their culls, friends’
tanks full of their culls…
Selling or marketing your culls is not always an option. Until the
traits you are working to established are “fixed”, in that the
majority of the fish you produce carry the trait, you do not want to
release poorly, inconsistently finned, poorly colored or
“half-assed” versions of your final product out to your eventual
customers. When you are finally able to sell the finished product,
you may find that there is no longer a market, because fishkeepers
already have tanks of inferior versions of the line you have
worked so hard on. And worse, they got them from you!
Your First Fish
When you buy fish from someone else to start a breeding program, the
fish are coming from foreign water, husbandry, food etc.
The goal from your first fish is to receive young born in your water.
With most fish, especially the livebearers, my experience has
been that those initial purchased individuals generally don’t live a
full lifespan. Their young should grow out well, and my experience
has been that getting fish into your tanks of the size and color of
those you saw at the website, or at the breeder’s fishroom, won't
appear until the second or third generation beyond the original stock.
So with guppies, for example, at 4 months per generation, assuming the
fish you receive drop within a month after you received
them, it will be another 8 months before you are working with fish that
display closer to the line’s potential. The best way to extend
the life of the fish you buy is to purchase young fish and raise them up
yourself. At the Select Aquatics, when obtaining a new
species, I have found that fish growing to their full-color and size
does not begin until into their third-generation.
This is why someone cannot purchase fry from a line of show winning
fish, then simply raise them up to win the same awards.
Any breeder will need to work with that line for at least two
generations before fish that come close to the quality of the original
can be produced.
I have also found that even with fish being kept in essentially empty
tanks beyond the water, fish, filter and possibly a heater, do
best when they are moved as little as possible. Consistent breeders need
to be allowed to stay where they are, even though the
water is the same throughout the room. The single biggest circumstance
where I lose fish is when I must remove a female and put
her in her own (generally smaller and more heavily planted) tank to drop
fry. Though it may be cleaner, and without issues of her
being harassed by the males, some species the fish may die shortly after
being moved, or she’s living, but only after having dropped
her young, all dead. A few species seem fairly prone to this, and with
others it is not an issue. With species most prone to this, you
can occasionally lose batches of young. (I have found that Ameca
splendens is one species that can be this way). So if there is only a
pair or trio in a tank by themselves, I may leave the female and remove
the others, then put in a cloud of plants until
she drops her fry.
You will also find that tank placement can greatly affect how well a
species will do, and whether it will reproduce for you.
Over time at Select Aquatics, I kept notes as to where each species did
best, and the differences could be substantial,
though the water quality was the same. A combination of the temperature
(some tanks placed higher were slightly warmer),
amount of light the tank received (some fish preferred being closer to
natural light coming in from a window), and the activity
directly outside of the aquarium seem to be the variables most
With species where the females are not removed to a tank of their own, I
will keep them well fed, put a bunch of plants in
for the babies to hide in, and then check the tank mid- late morning for
fry until they appear, as most livebearers generally
give birth between sun-up and noon. Then I’ll carefully remove whatever
I can catch, or remove the female and grow out
the fry in their birthing tank.
In any breeding program, one of the strongest components of your effort
is your ability to save every single fry, for you
never know which fish will carry the traits you are looking for, or a
new mutation appears that you will want to preserve.
The “rule of thumb” was that of a drop of 30 young, you may get one pair
worth keeping to consider as future breeders,
the rest will need to be disposed of, somehow. Out of a strained logic
to go natural, I started keeping something big
and carnivorous in its own tank to eat the culls, such as an Oscar. All
I ended up with was a fish that would go through
periods of feast or famine, who took up a large tank and space I really
needed for other things.
I learned that the function of any particular tank can change often, and
most problems can be solved by setting
up another tank, which can cause your fishroom to expand pretty quickly.
I recommend only keeping as many tanks
as you can effectively provide maximum care for, cull to keep numbers
down, and keep the number of strains you choose
to work with to a minimum. Don't let your strains multiply each time you
get a neat looking cull or two unless you are willing
to increase the number of tanks as needed.
And if females of two strains you are keeping near one another look
alike, the potential for an accidental cross by a fish
jumping between tanks is a real possibility- always separate tanks of
fish that look too much alike, or that could cross.
Creating greater numbers within a strain also increases your odds for
the appearance of a mutation.
The Easiest , Most Common Way to Screw Up
The biggest mistake a breeder can make is to accidentally mix two
similar looking species that may cross, or mixing two lines
that must be kept separate. If a mix continues and goes into the next
generation, the progress of any work on your line is stopped.
However, mating two species that will cross - most will not - is not
always an easy thing- a deliberate effort to cross two Xiphophorus
species, for example, is not a case of simply putting two of the
opposite sexes together. Having one or both species with
others of their own species in the tank further discourages their
breeding. Breeders trying to cross two fish that are not the
same species will often set up many pairings, alternating the sexes,
before a succesful fertilization. But with a mix of two lines
of the same species- however different in appearance- their crossing is
always a possibility.
Contamination between tanks often occurs by fish jumping, or by being
put there accidentally by you, or inadvertently
riding along as a fry in a bunch of plants or between the folds of a
net. With a consistent breeding program, contaminants
getting into tanks needs to be kept to a minimum. I am careful not to
keep tanks of closely related species near one another.
When establishing your water change routine, it took awhile for me to
determine what amounts should be changed for
the best effect for the fish. Though 35% a week is good, 5% a day is
both far better but much more work. I eventually
constructed an automatics Water change system (Youtube "Select Aquatics
Presents - Building an Automatic Water
Changing System and Keeping Rare Fish") Over time I have settled on
about 10% per day for my grow out and line
maintenance tanks, and the Pleco breeders have shown that they prefer
less frequent, but more substantial changes,
so they receive a 20-25% water change twice a week, and all tanks here
are also on central sump filtration.
(Youtube Select Aquatics Presents - Central Sumps and earning a Phd in
This water change system is entirely made of PVC that does not require
any drilling of tanks, and is relatively portable.
The PVC drain and fill tubing can be moved easily, and both the draining
and filling happen on their own.
Inbreeding and Appropriate Choice of Breeders
As I meet other hobbyists, I’d ask for advice, and found that otherwise
sensible, reasonable people will have strong
opinions on an aspect of husbandry or the breeding process. Someone who
believes in one approach can become
thought of as a nutcase by someone else, so it became important to
listen to everyone’s opinion, then figure out for
yourself whether any of the information applied to you..
To be honest, there may be no firm answers for many situations, and “the
truth” may vary from one fishroom to another.
What you feed, how often, your water qualities (pH, hardness,
temperature and how often you do water changes),
in combination with the characteristics of the species and line of fish
you are working with can contradict rules that
work well for someone else.
The result is that there are theories that are often the result of once
is an occurrence, twice is a coincidence, three times is
a rule, and these commonly held beliefs may not hold up on closer
inspection. One of these topics is inbreeding.
Does it weaken or strengthen the line? When should you outcross, if
ever? At the Xiphophorus stock center in San Marcos,
Texas, Dr. Gordon collected wild lines in the 1930’s that have been
inbred consistently for many dozens, and in some cases,
more than a hundred closely bred generations, and they are doing well
(with careful, extensive record keeping). So why do
fish that are inbred often show bent spines and such after just one or
two few generations?
The reason may be non-intuitive, but can be easily understood. As you
narrow the genetic diversity within a line of fish
through close inbreeding of similar, consistent, related individuals,
unwanted traits within the fish will gradually
show themselves as they “rise to the surface”. In other words, as each
aspect of the genetic diversity is
expressed over time, over a large number of fish, undesired traits that
are simply present within the genetic makeup of
some individuals will present themselves as the line becomes more
As the breeder you must cull those individuals, essentially removing
those negative traits from the genetic makeup of the
line, as you do with any fish that did not appear as you would like,
toward “purifying” or stabilizing the look of the line you
are working with. Bent spines are simply another trait that will appear
over the first three generations in many species, when
they are inbred, and those deformities will be bred out of the line by
the fourth or fifth generation.
Inbreeding is a commonly practiced, essential tool in the pet hobby.
When you see the rows of tanks of Sunset platys at
your LFS, for example, that are all healthy and nearly identical in
appearance, this is due to careful inbreeding over many
generations. The fish are fully healthy, but do possess a relatively
homogenous genetic makeup. This can be a problem in
some instances, such as with a wide resistance to disease, but they are
not unhealthy because of inbreeding.
If you were looking to develop a line of fish with debilitating
deformations, you would use those fish as breeders. (Balloon
mollies, anyone?) Fish with deformations or sometimes dramatic changes
in appearance (such as albinism) occur routinely
in the wild, but simply do not survive as they often present as a target
to predators. So the appearance of those negative
traits is not a response to the inbreeding “causing” a negative trait ,
it is simply the normal expression of traits the
fish carries, that it will eventually express, as a line loses its
variability and becomes more homogenous.
Inbreeding allows you to spot and remove the fish with these unwanted
traits most quickly from a population. One problem
with inbreeding however, is that without careful observation and
choosing healthy breeders, the line can deteriorate, as anyone
who has ever put a great line of guppies into a tank to community breed.
Within 2-3 generations they will revert toward reduced
coloring and smaller size.
In most cases, quality consistency, and appearance of developed traits
needs to be maintained through careful selection of
healthy breeders that will carry on the line.
Choosing appropriate breeders comes with close observation to select for
the largest, healthiest fish, that show a characteristic
you want to focus on. You would not choose a male guppy to be a breeder
with poor body shape or a weak overall physical
character, entirely because the tail is a particularly attractive color
you had never seen before. You could actually do
harm to the line with no guarantee that the color you desire will even
appear. With that situation, I would take the next best
males from the same brood, and breed the best of those to his best
sisters. Then raise up their young, looking for that color
I wanted, with the conformation and health that the original male did
not have. If a new male does show up that carries the minimum
characteristic you want to develop- then cross that male with his best
sisters to work to get a line started.
One trick used by guppy breeders, where the males possess all the color,
and the females do not, is to feed color foods
to the females before choosing them as breeders, to see the pallette and
strength of the colors that the female carries.
There are foods today that are not hormone based, that harmlessly
increase the color of the fish for the short-term (1-2 days)
and can be of value when making breeding choices. This can be much
appreciated when the colors contained by the female
are important, but cannot be seen. The female Odessa barbs are similar
to female guppies, where this can be a big help.
Breeding to develop a specific line requires discipline not to become
sidetracked by each new minor mutation,
as every differently colored or lushly finned fish is not necessarily a
healthy fish, and will require many additional tanks if you
choose to pursue it. To see a mutation in a single fish is a careful
process and a fair amount of time ( a couple years) until
you receive a batch of young carrying that trait. That is why I find
breeding so enjoyable- you get to form an idea, and then get
to see what the fish does with those choices that you make.
I choose breeders for traits I am looking for, aware that getting
something may requires a compromise of something else.
The biggest fish may not have the best color. The fish with the longest
fins may not be the largest fish. Etc. By having three or
four pairs or trios going at a time you can, over time, gradually nudge
the line toward the proper collection of traits you are looking
for, maintaining their overall size, health and vigor of the best fish
in the line.
With many of the Poeciliad livebearers, the largest males will be those
that sex out last, and using those males is essential
to develop or maintain a large size on your fish. However, you may need
to breed them before they have fully colored out,
or the sword isn't fully mature, because to wait too long could limit
the amount of reproductive time you will have with that fish.
I believe that hobbyists have begun to better understand inbreeding
today, though there are many that very reasonably
argue the benefits and essential place that outcrossing plays in many
breeding programs. This becomes more important
when dealing with other animals, such as breeding programs in zoos.
It comes down to what you are looking for, and the species you are
working with, (Discus breeders I’ve known can be
truly obsessed with the latest wild fish they’d paid to have caught and
shipped to outcross with) but I have come
to believe that inbreeding (brother to sister and parents to offspring)
by itself does not harm the fish, when breeders
are chosen appropriately. When an outcrossing to a wild fish occurs, the
next generation breeders must be chosen
carefully, as you are introducing any number of characteristics that may
need to be gradually bred out of the line over
many upcoming generations, to return the line to stability. Running
numerous pairs and trios in this situation
works best to choose the best individuals.
The Selective Breeding Process
Work to keep things simple. Tanks only require a strong and consistant
air stream to a large box corner filter
with charcoal and floss, a splash of gravel for nitrifying bacteria
area, kept reasonably clean. Live floating plants
with a heater with low to moderate light works best.
I have found that fry do best at slightly higher temperatures than the
adults to stimulate feeding and growth for tropical
temperature fish. (78-80 degrees seems to work best for
livebearer/cichlid/catfish fry. With colder water fish, such
as the Goodeids, the fry temp should stay around 73-74 degrees)
You want to provide the pH and hardness where the fish will breed
comfortably, and it is always best to breed fish that
are already suited to your tapwater. Bringing your pH or hardness up or
down can be done for the time of the breeding process,
but successful spawning and raising of the young can be difficult or
inconsistent. But it is certainly possible using crushed
coral or oyster shell (to bring up pH or hardness), or Oak leaves, alder
cones or muriatic acid to bring down the Ph.
Tanks are best with a simple, organized setup and consistent approach,
appropriate tank space, while keeping only fish
together that you want together without overcrowding. As a breeder, your
focus is on saving and raising the fry. Air and
temperature, moderate light, covers to prevent adults from jumping out,
and quality foods will meet any needs.
Include a few fine-leaved plants for security and to help water quality.
The Guppies taught me much I needed to know, but the reality was that I
left my total devotion to Guppies after
about 5 years. Much of their care involved compensating for immunity
problems from many generations of being
maintained in pristine conditions, to produce fish with huge fins that
had compromised circulation. I came to believe
that this resulted in their being prone to minor fin infections, leading
to more pristine care, and the fish's immune
systems continuing to decline over time.
The immunity issues I perceived could have been due to my husbandry, the
strains I worked with, or inherent immunity
weaknesses, though disease was never a problem for me in my tanks- the
problems arose when the fish left
my setup. Too often, I’d give fish to friends, they’d take them home and
the fish then died almost immediately. Today,
roughly 25 years later, the strains have improved, and there are a
number of lines bred by the IFGA, in Moscow, China
and in Israel that are much hardier and disease-resistant.
Depending on the species being worked with, and what is being done,
breeders will separate their fish based on brood,
or based on age. When compared to one another, it is something like
comparing an Xacto knife and an axe - keeping your
broods separate and tied to specific parents gives you much greater
control over your quality, and allows you to
breed more exactly. But it can also require more tanks, and when
compared to the quality of the fish produced that are
sorted by age (as I do), it is possible to achieve the same results
through larger numbers. The larger the numbers that
you produce, the greater the potential to produce fish that carry the
traits you are looking for.
Unfortunately, there are a few obstacles to consider, and most are
overcome through repeated or multiple efforts,
patience and persistence. Here is a rundown of what I try to be sure to
overcome for a successful breeding program to
1. Equipment setup. If you are occasionally running into problems with
the electricity going out, big temperature
fluctuations, tanks that leak, filters or heaters that are not
dependable, etc., then get those resolved first. I will use
only new heaters with an important breeding project. Use covered,
moderately lit, bare bottom tanks that stay at an
appropriate, consistent temperature, and simple floating plants (Java
moss, Java fern, Najas grass, riccia, water
sprite etc.) to keep things simple, stable and consistent. I will often
sprinkle a little gravel over 1/3 to 1/2 of the
bottom of the tank to provide nitrifying bacteria and aid filtration.
The focus must stay on the fish.
2. Get good initial stock, and be sure you can keep them healthy before
expecting them to breed for you. Poor
stock may not look as you prefer, and may not breed consistently, or may
even throw junk until you get the line
stabilized and predictable. That can take a lot of time- months-
however, when getting well bred, genetically stable
fish from a reputable breeder in the first place avoids those issues.
3. After the fish you receive are drip acclimated and settled in, their
young- the ones actually born in your water,
are the all important fish to focus on. Because it is the first
generation in your water, there may be some losses, and how
healthy and prolific they are will eventually be depends on how well
they are raised in your new environment. More will
survive, reach their potential and breed readily with each successive
generation as they acclimate to your conditions.
Until the line is stable- 2-3 generations, the numbers of young that
survive will improve, and the fish's colors, markings
and overall size will increase with each successive generation.
4. You cannot create a trait. These animals come with many hundreds of
characteristics that are no longer expressed,
but when a species is bred out in large enough numbers, or two
individuals are crossed with certain genetic mixes,
these long dormant traits will sometimes appear, and we will refer to
them as a mutation when we see them appear in
Most are detrimental to the fish, which is one reason why they are not
expressed more frequently, and when they
occur in the wild, the fish will rarely survive long with it (such as
albinism). But if the species does not contain the potential
for a trait in its genome, a spontaneous mutation of something never
seen before will sometimes, but rarely, occur. It is not
possible for you to breed for it, beyond creating a lot of individuals,
and hoping that an individual shows the trait you are
looking for, with the strong possibility that it may never be expressed.
The traits you work with and develop will come to you - you can't set
out, say, to develop a high fin Odessa
barb, unless you have an Odessa barb appear that carries that mutation,
or a closely related species has it that can be
crossed with the Odessas.
I have bred tens of thousands of my selectively bred Odessa barbs over
the past 13 years, and have yet to see either an
albino or a high fin fish. The trait has to occur on its own, I can't
set out to create it. Other closely related species, such as
the Rosy Barb, are bred with high fins, and albinos are also in the pet
trade, but the mating of high fin Rosie barbs with the
Odessas, something tried here on more than one occasion, has not
produced viable fry. So it is your job as the breeder to
keep a close eye on each fry that you produce, and identify those that
show something that might be of interest..
Predicting and Planning Egg Scatterer Output
Predicting the output of a species can be tricky. Assume we are talking
about a small egg layer- a barb, rasbora,
danio etc. How many young reach adulthood will be very different than
with Cichlids, for example, where the parents guard
the eggs and young, and where numbers may be lower. Most livebearers
with produce set broods sizes of 10-40 young that
are fairly well developed when first born. With egg layers that do not
guard their eggs, many more eggs are produced.
Many barbs may release 200-300 eggs with each spawn. However, the number
of fry that will reach 1 month old can vary widely,
for many reasons.
So you condition them, and the fully mature females are full of eggs and
ready to go, the males have been kept separated
and are also ready to go. You put them together under all of the correct
conditions and they eagerly spawn.
So you have spawned 3 females, and all dropped their eggs. However, you
will never grow out 900 fish. Your actual number
of fry reaching 1 month old, if you do everything right, in my
experience, will be closer to 150. If you set out with the assumption
that 2 pair of fish that can each lay 300 eggs every 2 weeks is going to
produce 1200 fish a month for you, you would be very
Here is why, starting from when they first spawn:
1. Not all females will spawn. With the Odessa Barbs, I generally put in
six females and three or four males, and often
two or three of them will not spawn. As well, only about 30%-50% of the
eggs laid will be fertilized, the rest fungus up,
and can look like snow over the bottom of the aquarium. But amazingly,
enough will have been fertilized to produce 300 - 500 fry.
2. Parents will eat some of the eggs. In the process of releasing eggs
over a divider during spawning, some will still be eaten.
The depth of the placemen of the divider needs to be roughly 1.5 inches
from the bottom, with water over the divider deep enough to
allow the fish to swim freely and comfortably to chase and dart about.
They also need to be able to get to food easily, so that it
does not simply fall through the screening when they are fed.
3. Negative Water quality spikes happen, and can often reduce the number
of fry. Avoiding your water clouding up by keeping
on top of water changes following feedings, or when cloudiness is seen,
will keep down losses due to water quality problems.
1. Air bladder development starts at birth, and many egg layers need to
be raised in shallow water. The water depth
is kept to 6 inches or below for the first 10-14 days, and the divider
is placed in the tank so that there is about 1.5 inches distance
for the eggs to fall to the bottom. I generally bring the fry to full
water depth by 30 days.
2. The period following their hatching does not need to be an uncertain
time of losses until they begin to eat regularly.
They will begin hatching in 24 hours , and frequent feedings, clean
water, and appropriate, gentle aeration are all you really need.
The filtration should be low or entirely the result of massive daily
seasoned water changes.
With livebearers, and plecos (I do 20-50% daily water changes for new
fry for the first week or two with smaller 10-29 gallon fry
rearing tanks) done so that few new fry are drained away, by siphoning
water from the tank through a net breeder. Once the smallest
fry are ready for brine shrimp, growth will go quickly, and they can be
moved into larger tanks at 14- 30 days, depending on the
size of the fry. Odessa barb fry are fed 3x per day, at 8am, 3 pm and 9
pm, with each feeding followed by a 50% water
change. Odessas are generally not moved to their own tanks until they
are 30 days old.
3. Micro-foods such as vinegar meals, microworms and Paramecium are used
for the egg layers, depending on the species,
and Baby Brine Shrimp is always in production and kept frozen in ice
cube trays for use on a moments notice.
4. Some will be born with issues that keep them from thriving. At first
I was breeding barbs in a tank that was too
deep, and easily 50% of my first spawns developed swim bladder problems.
They were unable to stay off the bottom, and
spent their days struggling to swim up, using their energy that should
have gone into growth. The majority were cured by raising
them in hanging net breeders where they stayed within 2-3 inches of the
water surface, removing them one by one as their swim
bladders developed properly. This took about 2 months, and resulted in
undersized fish, with some that never recovered.
Each species that you work with, be they egg layers or livebearers, will
each have its own tricks and idiosyncrasies.
Raising cichlid fry is different than raising egg scatterer fry, which
is different than raising killifish or rainbow fry, and
each of those are entirely different from harvesting livebearer fry.
Most will require their own types of tank set ups,
net breeders, tumblers or whatever-
5. You may be doing everything correctly, but with some species in a
normal location where they are exposed to
daily light cycles and seasonal temperature changes, they may naturally
stop breeding from about October to April
(depending on species), and there will be no young, or very reduced
spawns. This is the case with most of the species
at Select Aquatics, due to one wall being entirely windows. The
seasonality of the fish is different for many fish, and is
dependent upon where in the world they initially come from. But the
catfishes breed from November through
January, many of the Goodeids breed from December to April, and some of
the other Poeciliads will breed from
early April to mid June. Though difficult for planning sales, fish
breeding during their normal breeding seasons is
healthier for the fish, leading to healthier batches and longer lifespans.
You can breed and produce a lot of fish, but it will happen as a result
of your mastery of making it happen, not
the mathematics of what you assume is possible based on their
reproduction rates. You can make money at this, and
produce a lot of great fish, but like everything else, it doesn’t just
happen, at least not at first. The obvious
advantage of greater numbers are the mutations that could occur, and
careful choice of breeders
becomes far more interesting when there are a far greater number of fish
to choose from.
Choosing individual breeders can be challenging. With fast moving,
schooling fish such as the Odessa barbs, it can
be difficult to pull out a specific fish, particularly when they will
“wash out” when stressed, which is exactly what you trigger
when walking to the tank carrying a net. But there is a way to do it.
Remove any box filters from the tank, and the majority, but not all, of
the plants in the bare bottom tank. Leaving
some plants encourages them to hold on to their color. I then leave the
tank alone for a few minutes to let them settle
Then I take a 15 inch black fine mesh net and slowly enter it into the
aquarium so that it descends behind them as they
group toward the back of the aquarium. Then I bring the net forward
slowly to scoop up as many of them into the net
as possible. Then I lift up the net and place the edges against the rim
of the aquarium, so that it hangs down into the water.
Then, with a small net, I will slowly reach in and carefully remove the
best looking fish to be used as breeders. If there
are too many fish in the net, I will gradually remove the inferior fish
first, and release them into the tank to free up space in
the net. If I am looking for four males, I will choose six, putting them
into a separate container where they can sit
quietly. After setting the tank back up, I will then remove the two
weakest colored males of the six that I had pulled.
And then use the top 4.
Having a batch fail for any number of reasons will happen occasionally,
and you must realize that the fish spawn naturally,
and are releasing eggs on a regular basis. So when a batch fails, try to
determine the reason, learn from it, and then get
the tank cleaned up and reset up for the next effort, without making the
same mistake the next time around. I once restarted
spawning with the Odessas when batches failed 4 times in a row. It was
from that experience that I learned not to use females
older than three years old for breeding, and similar failures have not
occurred since. But that is how you learn- sure, you will
get that sick feeling in the pit of your stomach when a batch fails, but
you can only make value of that lost effort by starting over
again and learning from what went wrong the previous effort.
Mutations and Some Basic Genetics
I have been asked why I seem to get so many mutations, such as albinos
and leucistic fish -white individuals with black eyes-
among so many of my fish.
My getting the incidence of mutations is simply the result of observing
every young fry closely, then separating the
anomalous individuals from the others. They are then bred with one
another, or if only a single individual, I will breed that fish
with a normal colored sibling. Some of you may remember the Punnet
square from High School biology days, which more
clearly expresses what I am about to describe. This basic initial
introduction to trait genetics is all that I have needed to be
familiar with. However, you can certainly explore this subject further-
into sex linked characteristics, for example, with a decent
text on basic genetics.
The first spawns (The F1s) of the fish with the mutation, when mated
with a normal appearing sibling, will be all normal
colored, but the mating of two of those fish will produce spawns where
25% may produce fry that show the recessive
trait/ mutation of one of their their parents. (This would be the
second, or F2 generation). They will hopefully produce enough that
show the trait to breed them with one another, starting a new line,
where 100% may eventually show the recessive trait.
The fish showing the recessive trait, when bred to one another, will
produce all young carrying the trait- albino to albino will often
produce all albino young (but not always). 50% of that F2 generation-
the other siblings, however, though normal colored, will be
heterozygous (“Het”) for the recessive trait, and those, when mated with
one another will produce up to 25% young
that may show the recessive trait.
The remaining 25% of the F2 generation will be pure dominant, not
carrying the recessive mutation at all. So 75% of the
2nd generation spawn (the F2) is normal in appearance, and up to 25% may
show the recessive trait. Of the 75% normal
in appearance, 25% are pure dominant (they do not carry mutation) and
50% carry the recessive trait, but do not show it.
They will all look dominant, however, and it is not possible to
determine which carry the recessive trait, and which do not,
until you breed them with one another.
Generally, any new mutation will be weaker, undersized and possibly even
born with swim bladder problems.
Some may simply choose to treat these individuals with the special
“aquatic hydrovortex transition tool”
(flush them), but something different can be interesting, attractive and
desired by other hobbyists, and the trait may never
be developed without breeding out those individuals. These fish occur as
natural mutations, and must be grown out
to become as healthy as possible before being used to start a new line.
The high fin mayae were at first very undersized and weak, but through
generations of choosing the largest, healthiest
individuals, and crossing back, their size and constitution after about
4 years and 5 generations
began to approach the size and vigor of the normal fish that do not
carry the mutation.
With the “nezzy” (Xiphophorus Nezahualcoyotl) swordtails, from a batch
of roughly 30 young I would get three or
four whose growth would take off, both males and females, and they would
grow into large, husky, healthy fish.
I selected for those individuals. Their color and finnage might not have
been the best but their size and health needed
to be established at first. Then there would be a couple fish with great
color and finnage, healthy in all other
respects, but not as large, and they got set aside to later cross with
the largest individuals. Then, as with most
swordtails, there will be 3 or 4 “early-maturing” males in a drop that
sex out early and are undersized. This is an evolutionary
development that allows for some individuals to pass on their genes
early. Those must be removed from your breeding
stock. When the sword develops, the overall body growth stops and sexual
maturity will begin their spawning.
The best males are those that sex out late, looking similar to females
until secondary sexual characteristics
(The gonopodium and sword) develop . One fishkeeper that should know
better swears that some swordtails are born
females and change to males later in life, which will never happen. No
swordtails or mollies change sex and are
then fertile. Hobbyists are simply seeing later developing males. the
production of testosterone can occur as females
age, causing older females to show male characteristics, but those older
fish are never fertile as males or females.
I’d then set aside the remainder of the spawns as a “reserve” if
anything were to happen to the breeders. Rarely, there
will be fish in that reserve that will grow into big, nice looking fish,
outpacing those I had originally chosen. When picking
breeders, I select for a blocky, muscular shape and big finnage. As I
mentioned before, the interesting challenge
was choosing and putting together the best breeders after their promise
was clear, but before they had gotten too old.
The swordtails are said to possess 3 basic genetic paths, producing
large robust fish, midsized fish, and early maturing
males. My efforts are generally to focus on developing a line that is
primarily the largest, latest maturing individuals.
Myths, Non-myths and Truly Odd Beliefs
If you are to carry your head high as a breeder who claims to know what
you’re doing, you need to be aware of the
issues where expressing your opinion may get you into trouble. The trick
is to hold on to your opinions where everyone
will still get along with you, and let you see their setups. The problem
with the theories below is that both sides often have
a point, and it is easy to see why the conflicts continue. Only your own
experience will determine which side of the argument
you end up on.
Theory #1- Immunity Compromise
Addressed earlier, selective breeding with a developed line that has
been dramatically developed over a long period of time,
taken beyond its wild form in finnage and color, you may notice that the
fish are prone to fin rot and other bacterial
infections. They may be less prolific, or produce a greater percentage
of unhealthy young when kept as you would other,
non-line bred fish of the same species.
Guppy breeders I have spoken with are generally convinced that immunity
stays intact in the line-breeding programs
they use, and that tying any inherent weaknesses of their fish’s immune
system to line inbreeding and good clean living
is nonsense. They believe that like ourselves, the fish are exposed to
pathogens they fight off routinely, regardless of
water quality, and the infrequent fin rot occurrences can be controlled
with the use of salt in the water, careful attention
to cleanliness, quarantine of outbreaks and choosing breeders that are
healthy and strong. In fact, they may even believe
that simply culling any fish that become sick strengthens the immune
system of your line by preserving the healthiest fish.
They claim the fish are perfectly healthy, thank you very much. The long finnage has obvious circulation issues, and a carefully
bred fish with proportionate size and musculature should have no
problems with disease outbreaks.
The other side concludes that a long multigenerational history of being
raised in exceptionally clean, bare bottomed tanks,
selectively bred for finnage and color, produces fish that lose their
ability to fight off infection. The fish never face genuine
challenges to their immune system, and over many years of this
husbandry, it is no surprise that a sincere challenge to their
immune system results in quick deaths. Some guppy breeders even claim
they “don’t have any diseases in their fishroom”
further compromising their argument that fish are exposed to all
diseases all the time as a normal condition of aquarium water.
My experience tends to support the latter belief, but I have seen lines
of Guppies in the last couple years that
are much improved, and will grow out luxurious full delta tails, even
when kept in planted, gravel bottom tanks.
Those I have seen most frequently have been from European or Russian
stock, but it does indicate that the issue
is being addressed effectively, as can be seen in some of the quality
lines that are now available.
Is it necessary to outcross a carefully line bred fish, or possibly face
the eventual destruction/ collapse of
the line? I have been told that an outcross should occur by no later
than the 11th generation, and generally by
the 6th. Many breeders will separate a newly acquired stock into two
lines, line breed them separately, then
cross them with one another every 5th or 6th generation, as sort of a
compromise between the two schools of thought.
The genetic diversity is slight, but many feel that following that
practice is the best way to maintain the strongest
There are those that claim that outcossing to address concerns for
immune system strength are uneccessary, and that a
carefully bred line will stay perfectly healthy without outcrossing
(such as the fish produced by the Xiphophorus stock center
mentioned earlier). In fact, outcrossing is a risk that introduces
unwanted traits, flaws etc. into a line that has been carefully
developed to remove much of what you are re-introducing.
This is often what happens when a breeder decides to cross a highly
developed fancy line with a wild form to
“strengthen the line". You will find that this is one of those topics
that tends to bring out the color and finnage of the
My experience has been that “hybrid vigor” is certainly a real thing,
and outcrossing an established line to something
else will produce fish that are often more robust. But a careful program
of line breeding should be able to maintain
and continuously improve a line when done properly, without the need to
outcross. The Xiphophorus stock center, with
their line bred fish that go back over a hundred generations would seem
to prove that strict line breeding can be done
properly. Keeping two lines of a strain is certainly a good means to
outcross, and I imagine that some hybrid vigor should
result if the two lines had been allowed to develop independently for a
long enough period of time.
Theory #2- Growth Hormone Inhibitors
The first side of this theory holds that the largest “alpha” males in a
tank of single species fish secrete a substance that
functions as a growth inhibitor against other, younger developing males,
ensuring the physical dominance of the largest male.
This becomes a very important bit of information with male grow-out
tanks. Because of this, selecting for the largest
males for breeding is skewed toward one or two individuals that had
experienced a growth spurt at a young age, and then
may have suppressed the growth of their siblings. Choosing for other
traits such as color and finnage then becomes even
more difficult. Frequent water changes to dilute this chemical must be
done, as well as possibly separating out the promising
younger, but smaller males to other tanks so that they can grow out to
The other side holds that there is no such thing- after all, such a
substance has never been isolated and identified-
and that normal random growth advantages provide quicker access to food
and bullying of younger fish, creating the
It is accepted by most fishkeepers that something exists that has a
clear affect on the fish, in a manner that a
growth inhibiter would exhibit. However, when you are trying to raise up
young Xiph. Swords, a fish that can get
fairly large with the right feeding and water quality, It would
certainly be nice to know if such a substance exists,
and Identifying that substance would certainly answer a lot of questions fishkeepers have wondered about, but its
existence has yet to be proven. Like other breeders, the assumption of
its existence works well when developing large
fish, so I'll play along, because assuming that it exists does work.
Heavy water changes and raising the largest males away
from the others does produce the greatest percentage of larger fish.
Some also believe that young males may stunt their own growth in
response to visual cues received from larger males in
their territory. Others insist that only a relatively small percentage
of males are ever meant to be exceptionally large fish, and
though we can develop a line of predominantly large morph fish, the
presence of a range of smaller males is always to be
Theory #3- That Swordtails will Change Sex
No livebearer commonly said to possess this ability will ever change
from a sexually mature male or female into a
fertile, sexually mature member of the opposite sex. Most species of
fish mature at reasonably set rates that can be
predicted without problem when taking temperature, feeding, and light
cycles into consideration. So when a fish does
not fall within those rough parameters, we assume it is a very special
circumstance. With the poecilia velifera, for example,
I have had young males take up to a year to show a gonopodium, but that
fish had always been a male, it just just took an
exceptionally long time to sex out.
Theory #4- Community Breeding to Maintain the Wild Form
This holds that opposite the intent of selective breeding, a line
allowed to breed randomly in a single species tank
will strengthen natural, wild characteristics, ensuring that the fish
will become as close as possible to their original,
wild form. Sort of a selective breeding by “natural” means. This is
often cited by those breeding rare or wild type fish
who personally hope to divert the fish from its wild type as little as
possible, thinking this approach will yield the
closest to the continued appearance of the wild population.
The other side holds that an aquarium is an inherently artificial
environment, and that every effort to selectively breed
the healthiest, strongest individuals should be done, as these are the
fish most likely to survive in the wild, and breed
naturally, and are best suited to continue the line. When allowed to
breed indiscriminately, the artificial confines and
lack of predators picking off the weakest fish in the aquarium
encourages unhealthy fish to incorporate themselves into
the population, while self selecting for traits that provide an
advantage within the aquarium, but not necessarily in the wild
(such as smaller size). In my opinion, some will hold onto the flawed
assumption that we know how to develop a fish
that best represents its wild form, as a result of choices that we make
for the fish in our home aquariums.
My experience is that many fishkeepers holding the opinion that the wild
form can be maintained by leaving them
alone rarely provide an environment that addresses many aquarium
inherent modifiers. Keeping a larger, single species
tank that populates randomly is not difficult, particularly when your
concerns are providing enough plant cover to keep the
young from being eaten, and simply producing healthy fish.
A genuine effort to replicate a wild situation would require at least a
hundred gallon tank for a species that reaches an inch,
and then there would need to be the occasional introduction of
predators, cyclical live food, day/night temperature swings
and seasonal light and temperature variations to begin to head you in
the right direction. We can only do our best to raise
healthy fish, but we can’t claim that the fish we keep are exactly as
they would be in the wild.
Theory #5- Sell them so they Die!
This thinking is that when you have to go to great lengths to carefully,
selectively develop a line of nice looking fish,
and you are ready to sell those fish to someone else, it becomes the
responsibility of the customer to keep them as they
need to be kept, and telling them the lengths they may need to go to
provide a proper environment will only discourage the
sale. So it’s best to keep quiet. Some breeders feel that what the
customer needs to know will be the result of their research,
not your providing the information. If they die (as they often will),
they’ll have to come back to you for more fish anyway.
Essentially, if they leave your care and they look great and are in all
other aspects perfectly healthy fish, the fact that someone
else may not meet their needs is not, as the breeder making those fish
available to them, your problem. One wholesaler once
shared the advice that "once a fish leaves my doorstep it is no longer
On this I could not disagree more. The same applies to breeders that
feed color hormones to their fish before being
sold so they look better, not especially concerned that the fish could
be made sterile in the process, rationalizing
that the customer probably won’t breed them anyway. As a breeder you
have a responsibility to provide fish that meet
the customer’s reasonable expectations in as many ways as possible. Some
people can’t keep certain fish, due to their
water qualities or inexperience, granted. But I strongly believe that it
is up to the breeder to provide any and all information
the customer needs to keep them going, just as I would expect when I am
on the other side of the fence. I keep what I do
today in large part because of the information those first guppy
breeders gave me. Those original fish are long gone,
but the information has stayed with me, allowing me to continue keeping
Actually doing it. What steps are best right away?
Besides time, selective breeding requires space. the only way to
increase your odds for beneficial mutations is through
breeding larger numbers. Only through breeding a fish out by the many
hundreds will you increase your odds enough to
create genuine, spontaneous mutations. When first keeping Xiph. mayae, I
was in the process of making the line consistent
(breeding out the tendency toward early developing males, for example),
and was breeding them out 3-400 at a time in 40
gallon breeder tanks. And eventually, I did get my first albino after
about 3 years.
I have had other hobbyists tell me that an albino cannot be created
spontaneously, that a previous cross with an albino
fish had to have occurred. This is not true. Some species are more prone
to produce albinos than others, but in my
experience, many, if not most, species have the potential to produce
occasional, spontaneous albinos. The health and color
of the fish produced can vary widely, and some may be too weak to
Recently I obtained a single pair of longfin plecos with a greenish
tinge to them. The line had been badly hybridized, and though
there were many spectacular young being produced, many of the first
batches were a hodge-podge of various lines- albinos,
calicos, short fins and chocolates. The line needed to be made
consistent, and the quality of that consistency needed to
represent the best the line had to offer- excellent finnage and the best
green color that I could tease from the line. The line
has now been in production for 12 years, and until recently, 23 tanks of
29 to 55 gallons were devoted to just the
Longfin Green Dragons. Of all of those fish, roughly 170 top quality
Green Dragons were produced each year, of
thousands grown out. The remainder were short fins, albinos and fish of
poor color or finnage. The percentage of quality
longfin Green Dragons increases with each generation, and though they
have been going for 12 years, they are only in
roughly their ninth generation, and are still a ways from becoming
genetically stable, or breeding consistently.
So, what is “Selective Breeding?"
1. You start out with a pair of fish in a small bare-bottom, filtered
tank with a few fine leaved plants. (The tank being
small so that you can always see them easily, and they are able to find
food easily as they adapt to their new home),
and at least 3 other tanks to be used for that particular line of fish.
The size of the tanks must be comfortable in size
for the species you choose to work with. I have livebearers such as
guppies and swordtails in mind as I describe this
process, but the overall process for any species of fish would be
similar. Egg scatterers or egg layers providing large
numbers of fry will need special accommodations, but this set up can
also work for many egg layers such as killifish,
To provide security for young, this first tank should contain a moderate
amount of plants that fry can easily hide in.
(Java moss, Java fern, subwassertang, najas grass, riccia and water
sprite are some of the best.) The male, when the
female becomes gravid, is moved to a second tank, leaving the “home”
tank to the female. This way she can have her
young without the added stress of being moved.
2. For each line of fish you will need a minimum of 4 tanks. One for the
breeder pair, trio or pairs,
one for unsexed new fry, one for males grow-out and one for females
grow-out. This assumes that you will cull all of
the fish that don’t qualify as breeders, bringing your entire stock of
that line down to the few breeding pairs with each
generation. Keeping your culls, at least for a while, is best, for
occasionally a fish that had been passed over as a
breeder matures out into a huge fish, or one you may want to breed after
all. If you have a loss of your breeders, it is
also nice to know that you have fish in reserve. But 4 tanks gets the
3.When the young are born, remove the female right after she drops, and
either allow her to recover for 3-4 days in
another tank, or return her to the adult tank. Leave in a sprig or two
of Java fern or moss for the new fry to hide in, and to
help maintain water quality while also being a source of infusoria to
pick on. That now becomes the fry tank. Feed baby
brine shrimp lightly 2x a day to the new fry. With many egg layers, the
young will need to be raised up however necessary,
in a fry tank to then be separated by sex as they grow out.
If the fry tank is 5 gallons or smaller, change 50% of the water daily
with clean, seasoned water from another aquarium.
Do heavy water changes for their first 2 weeks. If possible, using aged
water from the tank where they were first born is
ideal, then add dechlorinated tap water to the parent tank. Around three
weeks, guppies can be sexed, while other species can
be watched closely for the first signs of sexing out. More information
on breeding's egg scatterers can be seen in the YouTube video
"Breeding Odessa Barbs, selectaquatics.com Vids 1, 2 ,3."
Move the sexed females first to their own tank, this will ensure that
few of your females will have been fertilized. For livebearers
where the mature males possess a gonopodium, separate sexes as soon as
the gonopodium development is seen, or
a darker “gravid spot” begins to appear on the females behind the
“belly” area. Once a working gonopodium is in place,
the males can mate, regardless of whether other secondary sex
characteristics have occurred (such as the development
of a sword). Raise male and female groups separately to sexual maturity.
By separating the sexes you are not only
preventing unwanted breeding, but you are also substantially increasing
the growth and size of the fish, as they are not
expending energy chasing one another to compete while trying to breed.
4. Raise them up to determine which will be early maturing males,
undersized, or otherwise unhealthy fish, and remove
those individuals. Move bigger, later maturing males and all fish that
may become breeders to a tank of their own to provide
more space and better water conditions, or if maintaining just 4-tanks,
cull inferior fish. Continue the process with the females
as well, choosing for size, color confirmation, etc. Save the culls if
possible (in case something happens to the better ones).
It will be at this point that you will need to make decisions such as:
should I choose one fish that is larger and more robust, whose
color isn’t so great, or should I choose this other fish, whose color is
spectacular, but is undersized? If you have the
spare tanks, you would do both, and then possibly cross the best young
that each mating produces. Without the extra tanks, the
decision is yours, but overall size takes a long time to reclaim when
lost. The basic rule, when selecting for traits, is to first select
for overall size, then finnage, then color.
5.Raise them up to when size, color, and finnage are set enough to
compare one against another, and choose the best fish.
With guppies this is at about 3.5-4 months, with swords it can be
substantially longer- 6, 7 months. These are your breeders.
Generally, a rule of thumb is that of a batch of 30 babies, you will get
1-2 pair that will be breeders.
6.Continue the process until your breeder pairs are producing young that
consistently carry the trait you are looking for.
I have been told that it takes 11 generations to fix a trait, so that it
becomes as consistent as it is going to get- where
ideally every young in the brood expresses the trait. With guppies a
generation is 4 months, with helleri swordtails and
platies, a generation is 8 months, with angelfish and most cichlids it
is closer to 10 months. My experience has been that
I start to see acceptable consistency (70-80% of young carrying the
trait) by the 6th generation.
7. It is possible to have your selective breeding program "Crash" on
you. Say you are breeding for long finnage on a pretty fish.
You are faced with a tank of young sexed adolescents that are a
combination of fish at various sizes and health, color quality, and
finnage length. Over time you will get a feel for making the best
choices where the traits you want will likely show up in the young
that your choice of breeders produce. One basic rule that I follow is
that with these longfinned, pretty fish being used as an example,
I will first develop a robust longfin fish first, without specific
concern for the color. Then, when I have a decent sized group of
consistently robust longfin fish, I will then select breeders with the
best color. (Remember: Size, then finnage, then color.).
If I try to move too quickly, making changes in both the finnage and
color, selecting for more than one or two traits at a time, without
the proper attention to their size and overall health, you could produce
fry that are a worthless mishmash, and that don't
produce the traits you are looking for. So when you are selectively
breeding, the pace of introducing traits, and how you go about
establishing them, is where experience and skill come into play. Moving
too quickly can cause your line to crash.
Do things right the first time, and don't compromise or take short cuts.
Change the filter floss every couple weeks, and everything
else comes down to regular water changes, types of food fed in small
amounts as often as possible, proper temperature,
aeration, critical observation and patience. I also read constantly from
every book and magazine I can find on any and
all of the fish that I am working with.
You must feed newly hatched brine shrimp to the fry and a good dry food
daily, possibly with beefheart or chicken liver
mix a couple times a week. I also use the “Golden Pearls”, produced by
Brine Shrimp Direct, and often feed smaller new fry
a mix of powdered dry food dissolved in water. I also feed live daphnia
and other live foods. The biggest killer of new fry is mulm,
collected debris, and inconsistent tank or water conditions.
I find that I'm constantly challenged, and pleased with new and
interesting things that seem to happen almost daily. I often wondered
if focusing on just a couple lines could become boring or a burden, but
the secret is to keep it simple and within your time, energy
and budget. Keep your projects exciting, fresh and challenging. Today I
happen to think that the bare bottomed tanks look great- I
don't miss the gravel and landscaping. The emphasis is now totally on
the fish. And what I ended up with is certainly a long way from
what I had expected, back when I thought I knew what I was doing!